Expedience/Expedience.Api/Controllers/ExpedienceController.cs

using System;
using System.Net;
using System.Text.Json;
using Expedience.Api.Encryption;
using Expedience.Infrastructure;
using Expedience.Infrastructure.Concurrency;
using Expedience.Infrastructure.Models;
using MassTransit;
using Microsoft.AspNetCore.Mvc;

namespace Expedience.Api.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ExpedienceController : ControllerBase
    {
        private readonly ILogger<ExpedienceController> _logger;
        private readonly IPublishEndpoint _publisher;
        private readonly IDecryptor _decrypytor;
        private readonly IDistributedLock _distributedLock;
        private readonly IServiceScopeFactory _serviceScopeFactory;

        public ExpedienceController(ILogger<ExpedienceController> logger, 
            IPublishEndpoint publisher, 
            IDecryptor decrypytor,
            IDistributedLock distributedLock,
            IServiceScopeFactory serviceScopeFactory)
        {
            _logger = logger;
            _publisher = publisher;
            _decrypytor = decrypytor;
            _distributedLock = distributedLock;
            _serviceScopeFactory = serviceScopeFactory;
        }

        [HttpPost("DutyCompletion")]
        public async Task<ActionResult> PostDutyCompletionResult(List<string> encryptedPayloads)
        {
            var utcNow = DateTime.UtcNow;
            try
            {
                foreach (var payload in encryptedPayloads)
                {
                    var decryptedData = _decrypytor.Decrypt(payload);
                    var completionResult = JsonSerializer.Deserialize<Models.DutyCompletionResult>(decryptedData)!;
                    completionResult.UploadDateUtc = utcNow;
                    await _publisher.Publish(completionResult);
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error publishing completion result: {errorMessage}", ex.Message);
            }

            return Ok();
        }

        [HttpGet("UserName/{worldId}/{userHash}")]
        public async Task<ActionResult> GetUserName(int worldId, string userHash, CancellationToken cancellationToken)
        {
            using var scope = _serviceScopeFactory.CreateScope();
            using var dbContext = scope.ServiceProvider.GetRequiredService<ExpedienceContext>();

            var lockKey = $"{worldId}-{userHash}";
            if (_distributedLock.AcquireLock(lockKey, TimeSpan.FromSeconds(10)))
            {
                try
                {
                    var user = dbContext.Users.FirstOrDefault(x => x.UserHash == userHash && x.WorldId == worldId);
                    if (user == null)
                    {
                        string userName;
                        var isDuplicate = false;
                        do
                        {
                            userName = UserNameGenerator.Generate();
                            isDuplicate = dbContext.Users.Any(x => x.WorldId == worldId && x.UserName == userName);
                            await Task.Delay(20, cancellationToken); // Don't hog the CPU
                        }
                        while (isDuplicate == false);

                        user = new User
                        {
                            UserHash = userHash,
                            WorldId = worldId,
                            UserName = userName,
                            CreatedAt = DateTime.UtcNow,
                        };

                        dbContext.Users.Add(user);
                        await dbContext.SaveChangesAsync(cancellationToken);
                    }

                    return Ok(user.UserName);

                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Error obtaining user name for World Id {worldId} and hash {userHash}: {errorMessage}", ex.Message);
                }
                finally
                {
                    _distributedLock.ReleaseLock(lockKey);
                }
            }
            else
            {
                _logger.LogError("Could not acquire lock for {lockKey}", lockKey);
            }

            return StatusCode(500);
        }
    }
}